diff --git a/glue/viewers/image/state.py b/glue/viewers/image/state.py
index 31cc9f50b..3a5c6db8b 100644
--- a/glue/viewers/image/state.py
+++ b/glue/viewers/image/state.py
@@ -492,8 +492,8 @@ class ImageLayerState(BaseImageLayerState, StretchStateMixin):
     v_min = DDCProperty(docstring='The lower level shown')
     v_max = DDCProperty(docstring='The upper level shown')
     attribute_display_unit = DDSCProperty(docstring='The units to use to define the levels')
-    percentile = DDSCProperty(docstring='The percentile value used to '
-                                        'automatically calculate levels')
+    percentile = DDSCProperty(docstring='The percentile value used to automatically '
+                                        'calculate levels; "Custom" for manually set levels')
     contrast = DDCProperty(1, docstring='The contrast of the layer')
     bias = DDCProperty(0.5, docstring='A constant value that is added to the '
                                       'layer before rendering')
@@ -501,9 +501,9 @@ class ImageLayerState(BaseImageLayerState, StretchStateMixin):
     global_sync = DDCProperty(False, docstring='Whether the color and transparency '
                                                'should be synced with the global '
                                                'color and transparency for the data')
-    global_limits = DDCProperty(True, docstring='Calculate automatic levels on statistics '
-                                                'over the entire data cube or only the '
-                                                'current layer (slice)')
+    stretch_global = DDCProperty(True, docstring='Calculate automatic levels for rendering '
+                                                 'stretch from the full data cube or only the '
+                                                 'current layer (slice)')
 
     def __init__(self, layer=None, viewer_state=None, **kwargs):
 
@@ -545,7 +545,7 @@ def format_unit(unit):
 
         self.add_callback('global_sync', self._update_syncing)
         self.add_callback('layer', self._update_attribute)
-        self.add_callback('global_limits', self._set_global_limits, priority=0)
+        self.add_callback('stretch_global', self._set_global_stretch, priority=0)
 
         self._update_syncing()
 
@@ -585,8 +585,8 @@ def _update_syncing(self, *args):
     def _get_image(self, view=None):
         return self.layer[self.attribute, view]
 
-    def _set_global_limits(self, global_limits=True):
-        if global_limits:
+    def _set_global_stretch(self, stretch_global=True):
+        if stretch_global:
             self.viewer_state.remove_callback('slices', self._update_slice_subset)
             self.attribute_lim_helper.set_slice(None)
         else: